Ultrasonic fingerprint scanners: how do they work?
Besides the recent announcement of the world’s first Qualcomm Snapdragon 820 powered smartphone, the Le Max Pro smartphone also packs in a rather interesting sounding Qualcomm Sense ID ultrasonic fingerprint scanner. Let’s take a closer look at how this technology works and what sort of advantages it has to offer over current fingerprint scanning technologies on the market.
Rather than existing photographic or capacitive based fingerprint scanners, Qualcomm’s Sense ID makes use of ultrasonic sound, as the name implies, in order to map out the details of the user’s fingerprint. Fortunately, there’s no need to swipe, just touch the finger to the sensor like the top of the line capacitive fingerprint scanners.
To actually capture the details of a fingerprint, the hardware consists of both a transmitter and a receiver. An ultrasonic pulse is transmitted against the finger that is placed over the scanner. Some of this pulse is absorbed and some of it is bounced back to the sensor, depending upon the ridges, pores and other details that are unique to each fingerprint.
There isn’t a microphone listening out for these returning signals, instead a sensor that can detect mechanical stress is used to calculate the intensity of the returning ultrasonic pulse at different points on the scanner. Scanning for longer periods of time allows for additional depth data to be captured, resulting in a highly detailed 3D reproduction of the scanned fingerprint.
This is considerably different to even the best capacitive fingerprint scanners on the market at the moment, which are only able to reproduce 2D images. 3D details are much more difficult to forge or fool than 2D versions of the technology, potentially making the ultrasonic system much more secure.
Another added perk of this ultrasonic fingerprint scanner technology is that it allows the fingerprint scanner to still operate through thin materials, such as a smartphone case built from glass, aluminium or plastic. Therefore, the scanner can be embedded under the case, allowing for a more discrete look. Additionally, there’s less chance of damaging the sensor or exposing it to external tampering, and sweat or moisture on the finger won’t interfere with the scanning process either.See also: Fingerprint fight: Galaxy Note 5 vs Mate S vs iPhone 6S
Of course, there’s still plenty to be done with this fingerprint data and keeping it secure is an equally important part of the system. Qualcomm’s Sense ID technology is built on the Qualcomm Biometric Integrated Circuit (QBIC). This unit communicates with the sensor hardware and houses the algorithms necessary to make sense of the data on chip. This IC can then communicate with the main Snapdragon SoC that powers your smartphone, where the fingerprint data can be used by software.
Qualcomm’s Secure MSM architecture in its Snapdragon processors provides additional protection via a separate execution environment that is kept away from the rest of the high level operating system. Secure MSM is traditionally used to handle cryptographic and other sensitive bits of data. This way, important user security information is kept secure on its own piece of hardware and in a separate software bubble away from potential malicious bits of code.
Qualcomm’s Sense ID setup also supports the Fast Identity Online (FIDO) Alliance protocols, which can be used for online password-less authentication, without transferring any of the confidential fingerprint information to the cloud or through networks that could be compromised.
Ultrasonic fingerprint scanners certainly have a number of advantages of existing capacitive implementations and given the prevalence of Qualcomm processors in mobile products, we can probably expect to see the technology in a number of smartphones this year. Qualcomm’s Sense ID is likely to be only one of the first ultrasonic systems to make its way to the mobile space.